Energy absorbing safety wall for motor racing

ABSTRACT

The “Finned Friction Wall” is an energy absorbing safety wall designed to improve the level of safety in motor racing sports (and can also be used to improve public road safety if implemented). The FFW provides a safer collision due to the fact that it absorbs and dissipates much of the energy created by the impact of the racing vehicle into the wall. A typical FFW is constructed of 4′×8′ steel panels with closely spaced “fins” welded vertically at a deflecting angle of 30 to 45 degrees from the wall leaning in the direction of traffic. The energy absorbing and dissipating features of the FFW set it apart from other safety wall designs.

[0001] Our term for the energy absorbing/dissipating safety wall described in this document is the “Finned Friction Wall” (also referred to as the “FFW”). The “Finned Friction Wall” is an energy absorbing safety wall designed to improve the level of safety in motor racing sports (and can also be used to improve public road safety if implemented).

[0002] The “Finned Friction Wall” is a specially fabricated, mild steel, energy-absorbing barrier between the concrete walls and the racing vehicles. A typical FFW is constructed of 4′×8′ steel panels with closely spaced “fins” welded vertically at a deflecting angle of 30 to 45 degrees from the wall leaning in the direction of traffic.

[0003] A typical “fin” is a piece of steel ¼″ thick, 8″ wide, and 4′ high (to match the height of the steel panel to which they are attached). Fins are spaced at different distances apart (approximately 2″), depending on the speed, weight, and other characteristics of the race vehicles at a given track. Fins are attached to the panels by continuous fillet welding.

[0004] The steel plate with welded fins is bolted to the existing concrete wall with the fins leaning in the normal direction of traffic flow. The back panel of the wall is through-bolted to the concrete wall using high-strength fasteners. The steel panels overlap to prevent them from being peeled from existing concrete supporting wall. 

1. The FFW provides a safer collision due to the fact that it absorbs and dissipates much of the energy created by the impact of the racing vehicle into the wall.
 2. Other “safe” wall designs may somewhat cushion the initial impact of a vehicle, but then they transfer the energy they absorb right back to the vehicle. A good example is a billiard ball striking the rail of a billiard table. The rail (which represents the typical “safe” wall) absorbs the impact of the ball (which represents the racing vehicle), but then immediately transfers that energy back to the ball causing it to bounce off the rail. When an impact is made into the FFW, the fins are bent and do not spring back fully. The fins rub adjacent fins as they are bent and much friction is produced. This dissipates the energy, which therefore does NOT get transferred back to the vehicle.
 3. The energy absorbing and dissipating features of the FFW set it apart from other safety wall designs. Several factors contribute to the FFW's ability to disperse the energy it absorbs. First of all, the fins are not typically “springy”. They bend upon significant impact and do not spring back fully. Also, the fins bend into neighboring fins, which lends further support and produces friction. The production of friction is where the FFW transfers its energy—not back to the racing vehicle. Not only do the impacted fins assist in this operation. Depending on the closeness, width, thickness, and angle of the fins (which can be tailored for specific racing environments), friction between adjacent fins can continue several feet down-track from the initial impact.
 4. In addition to the energy dissipating qualities of the FFW, it provides another important benefit—deflection of head-on or near head-on collisions. Since the fins are angled in the direction of normal traffic flow, a vehicle impacting the fins will cause the fins to bend. As the fins bend, the vehicle will be slightly turned in the direction of the bend. This in itself reduces the severity of the impact.
 5. Due to the fact that the energy produced during a collision is first absorbed, then dissipated, it is clear that the injuring impact on the driver is reduced.
 6. For the same reasons (energy absorption and dissipation) impact damage to the vehicle is reduced. Structural integrity of the frame of the racing vehicle is more likely to be maintained. Besides the fact that this is safer in itself, the result of a softer vehicle impact allows other safety features of the vehicle (roll cages, etc.) to retain their effectiveness.
 7. The “softer” collision will make it more likely that driver controls, such as steering and brakes, will remain enabled. Drivers will therefore be better able to maintain control of the vehicle after impact. These factors will make it possible for the drivers to avoid further collisions with other racing vehicles.
 8. All but the worst of collisions leave the wall effective in its energy absorbing capabilities. The bent fins, unless totally flattened against the steel back panel, will still provide energy absorption by bending further, and energy dissipation by the friction resulting from them rubbing with neighboring fins.
 9. Should the wall be rendered ineffective, emergency repairs can be done quickly during the race by replacing sections as needed using ordinary power tools. The sections can be lifted from the wall using various means (tow truck for example).
 10. These energy absorption and dissipation claims also apply to non-racing purposes such as public roads having side and median barriers. 